This invention relates to transmission of video and audio baseband signals.
A present and future need exists to bring video and audio signals to the desk, for example, to provide security monitoring, factory production monitoring, training, and video conferencing. Such information needs usually require the installation of shielded wiring or optical fiber cables. It would be more economical to utilize wiring which is already available within the physical structure, i.e., the unshielded twisted pair cables used for transmission of analog voice signals. However, a problem exists in preventing undue crosstalk between the video and audio twisted pairs which are located within the same cable sheath.
Some vendors have suggested applying video and audio signals to twisted pair by means of an active interface which shapes and amplifies the signals (see U.S. Pat. No. 5,130,793 issued to Bordry et al.). However, this approach is expensive. It would be far more economical to provide an adapter which will permit coupling of the video and audio channels in a "passive" rather than an "active" manner.
Further, it does not appear that anyone has suggested the application of dual channel audio signals to twisted pair wiring.